When a tire attached to an automobile or the like includes a portion that has a non-uniform dimensional shape or a non-uniform elastic modulus in the circumferential direction, such portion causes a vibration during a high-speed rotation, and degrades the running performance of the automobile or the like. For this reason, the tire is subjected to a circumferential uniformity test by a tire testing machine after a vulcanizing process. The tire testing machine performs a test in a manner such that a bead portion of the inner periphery of the tire is fitted or “chucked” onto separate first/lower and second/upper rim members provided on respective first/lower and second/upper spindles or chuck assemblies, the tire is inflated to a predetermined inner air pressure, and the tire is rotationally driven while the outer periphery of the tire is pressed against a road surface simulation member such as a rotating drum. In general, lubricant is applied to the bead portion of the tire to be tested in order to smoothly fit the tire onto the rim members. In such tire testing machines, it is known to convey a tire to be tested to a center or testing position where it is chucked as described above for the testing operation.
In one known machine, a front end of a tire on a conveyor and a rear end of the tire are detected by sensors respectively provided at predetermined positions, and the tire to be tested is conveyed to the center position of the spindle, and a conveying distance from the predetermined position at the entrance side of the test station is calculated based on the calculated outer diameter of the tire.
Further, in another known tire testing machine, a tire is centered and conveyed a predetermined distance, to where the tire matches a rotation axis of a spindle assembly, using the conveyor. Then, when the tire is located in the testing position, the conveyor is caused to descend downward in relation to the spindle assembly, and the tire chucking operation is performed by the spindle assembly.
In these known systems, the tire chucking operation is not initiated until the tire is located in the testing position with respect to the conveying direction and, for this reason, the tire test time (i.e., the cycle time) in known tire testing machines is negatively lengthened. Meanwhile, when the chucking mechanism that drives one or both spindles including the upper and lower rim members is operated with excessive acceleration speed or an excessive deceleration speed in order to shorten the cycle time, a problem arises in that the actuator(s) increase in size and cost and component wear increases. Further, when the speed of the tire testing machine conveyor, itself, increases, a problem arises in that the tire may slip relative to the conveyor and not be conveyed as intended or expected on the conveyor.